Complete achromatopsia is an inherited retinal disorder characterized by severely reduced visual acuity, nystagmus, severe photophobia, a small central scotoma, eccentric fixation, and complete loss of color discrimination. In 50% of patients with achromatopsia the disease is caused by mutations in the cyclic nucleotide gated channel beta subunit (CNGB3) gene. Preliminary studies indicate that gene therapy using a recombinant adeno-associated virus serotype 5 (rAAV5) vector expressing a human CNGB3 gene can restore cone photoreceptor function in a dog model of achromatopsia caused by mutations in the CNGB3 gene. The objectives of the studies proposed in this application are to confirm and extend these findings using a rAAV5-CNGB3 vector produced using a commercially relevant manufacturing method. This will be accomplished by producing and purifying a rAAV5-hCNGB3 vector and evaluating the safety and efficacy of subretinal administration of a range of vector concentrations (1 x 1010, 1 x 1011, and 1 x 1012 vg/mL) of the rAAV5-CNGB3 vector in a dog model of achromatopsia caused by mutations in the CNGB3 gene. Results of these studies will be important for future advanced development of rAAV-CNGB3 gene therapy for evaluation in patients with CNGB3-related achromatopsia. PUBLIC HEALTH RELEVANCE: Complete achromatopsia is an inherited retinal disease characterized by severely reduced visual acuity and complete loss of color discrimination. In 50% of patients, the disease is caused by mutations in the CNGB3 gene. No treatment for achromatopsia is currently available. This project will evaluate a novel, CNGB3 gene therapy product for treatment of achromatopsia in a dog model.